_Peduncle_, barely as long as the capitulum, apparently (for specimens dry and much shrunk) narrow, surrounded by rings or folds of thicker yellowish membrane, of which the upper ones retain moderately long spines; low down these rings become confluent; whole surface finely dotted, dots largest on the rings.
_Mouth._--Labrum highly bullate in the upper part, with a row of teeth on the crest; mandibles with four teeth, the fourth close to the inferior apex, which is very little developed, sometimes making the fourth tooth appear simply bifid. Maxillae with two large spines on the upper angle, beneath which there is a large depression, bearing one rather long and thick, and four short and thick, spines; inferior upraised part with a double row of longer and thinner spines.
_Cirri._--Posterior cirri with segments bearing five pairs of spines, of which the lowest pair is very minute; intermediate spines minute; spines of the dorsal tuft thin, of nearly equal size; segments not at all protuberant, elongated. First cirrus, standing far separated from the second (as in Scalpellum), with its nearly equal rami rather above half as long as those of the second cirrus. Second cirrus with anterior ramus not thicker, and scarcely more thickly clothed with spines, than the posterior ramus, but shorter than it by three or four segments; the spines not forming a very thick brush on the anterior ramus. Both rami of third cirrus with a longitudinal row of minute spines, parallel to the main pairs. Between the bases of the pedicels of the first pair of cirri, there are two closely approximate, conical flattened protuberances, like the single one to be described in Ibla.
_Caudal Appendages_, about one third of the length of the pedicel of the sixth cirrus, with some moderately long and strong spines at the end, and down the whole outer sides.
_Ova_, much pointed. _p.e.n.i.s_, hairy.
_Size._--Capitulum in largest specimens half an inch long.
2. PaeCILASMA AURANTIA. Pl. II, Fig. 2.
_P. valvis 5; carinae basi truncata: scutis ovatis, margine basali perbrevi, dentibus parvis, internis, umbonalibus instructo: tergorum ac.u.mine basali peroblique truncato._
Valves 5; carina with a truncated base; scuta oval, with the basal margin very short, furnished with small internal umbonal teeth; terga, with the basal point very obliquely truncated.
Maxillae with fine spines in the notch under the three great upper spines; caudal appendages with scattered bristles on their summits, and along only the upper part of their outer margins.
Madeira; found by the Rev. R. T. Lowe, attached to the rare _h.o.m.ola Cuvierii_, probably a deep-water crab. British Museum.
_General Appearance._--This species so closely resembles _P. Kaempferi_, that it is superfluous to describe it in detail; and I will indicate only the points of difference. When the valves have been well preserved, they are of fine pale orange colour, and hence the name above given, which was proposed by the Rev. R. T. Lowe.
_Scuta_, with the internal umbonal teeth small; basal internal marginal rim very prominent, furrowed within; basal margin short, (only equalling half the length of terga), owing to the great curvature of the lower part of the carino-tergal margin; hence, the outline of the scuta is almost pointed oval. I saw no appearance of inequality in the two sides.
_Terga_, rather smaller in proportion to the scuta, than in _P.
Kaempferi_, with the basal end very obliquely truncated, so as to appear at first simply pointed, not parallel to the occludent margin; apex considerably more pointed and produced than in the foregoing species.
_Carina_, almost of equal narrowness throughout, barely concave within; lower end triangular, abruptly truncated, and not crested.
_Primordial valves_ very plain, with the usual hexagonal structure: those of the terga, rounded at both ends, instead of being square, as in the mature calcified valves.
_Peduncle_ short, narrow, not half as long as the capitulum; paved with minute equal beads, as in the genus Dichelaspis.
_Mouth._--Mandibles with the fourth tooth very small; inferior angle rudimentary. Maxillae, with three great upper spines, beneath which there is a deep notch bearing some delicate spines; inferior upraised part, as in _P. Kaempferi_.
_Cirri._--Rami of first cirrus hardly more than one third as long as the rami of the second cirrus, which latter rami are unequal in length by only two segments; the posterior ramus being the longer one.
_Caudal Appendages_, with only two or three lateral bristles, besides those on the summit.
_Size._--Capitulum, three to four tenths of an inch long.
_General Remarks._--This species has the closest general resemblance to _P. Kaempferi_, and is evidently a representative of it. On close examination, however, almost every part differs slightly; the chief points being the narrowness of the basal margin of the scuta; the obliqueness of the truncated basal end of the terga and the sharpness of the upper end; the rudimentary state of the inferior angle of the mandibles; the character of the spines on the maxillae; the proportional lengths of the cirri, and the fewness of the spines on the outer sides of the caudal appendages. The fact of Madeira having this Paecilasma, a representative both in structure and habits of a j.a.pan species, is interesting, inasmuch, as I am informed by Mr. Lowe, that some of the Madeira fishes are a.n.a.logues of those of j.a.pan.
3. PaeCILASMA CRa.s.sA. Pl. II. Fig. 3.
ANATIFA CRa.s.sA. _J. E. Gray._ Proc. Zoolog. Soc., 1848, p. 44, Annulosa, Tab. iii, figs. 5, 6.
_P. valvis 5; carinae termino basali in disc.u.m parvum infossum producto: scutis convexis, dentibus internis umbonalibus nullis: tergis paene rudimentalibus, vix carina latioribus._
Valves 5; carina with the basal end produced into a small imbedded disc; scuta convex, without internal umbonal teeth; terga almost rudimentary, scarcely broader than the carina.
Spines on the segments of the posterior cirri arranged in single transverse rows.
Madeira; attached to the _h.o.m.ola Cuvierii_, Rev. R. T. Lowe.
British Museum.[31]
_General Appearance._--Capitulum highly bullate, or thick. Valves rather thick, opaque, either pale or dark flesh-red, smooth, yet rather plainly striated from the umbones. There are a few very minute spines on the membranous borders of the valves.
_Scuta_ highly convex, broadly oval, apex broad rounded; basal margin narrow, much curved; no internal, umbonal teeth; basal internal rim strong, running up part of the occludent margin. A slightly prominent ridge, either rounded or angular, but in one specimen a narrow depressed fissure-like line, runs parallel to the occludent margin and ends near the apex in a slight notch; this fact is of interest in relation to the structure of the scuta in _P. eburnea_ and _P. fissa_. The scuta are either equally or very unequally convex; in the latter case, the occludent margin of one valve is curled, so that its umbo is not quite medial.
[31] It is stated, in "Zoolog. Proc.," (1848, p. 44,) that this species was attached to a gorgonia, from Madeira; I cannot but suspect that there has been some confusion with the _Oxynaspis celata_ from Madeira, which is thus attached.
_Terga_, minute, almost rudimentary, scarcely broader than the carina, and half as long as the chord of its arc; carinal margin slightly curved; scutal margin straight, with a slight prominence fitting into a notch in the scuta; basal end bluntly pointed.
_Carina_, (fig. 3, _a_) rather shorter than the scuta, extending up only to the basal ends of the terga; moderately curved; apex moderately sharp; middle part broadest, externally carinated; internally not concave, with the inner lamina of sh.e.l.l, at the basal end, produced into a very small oblong disc or tooth, which is only as wide as the narrowest upper part of the valve. The exterior keel does not extend on to this disc, which is slightly constricted at its origin.
_Peduncle_ very short, narrow, ringed, and apparently without spines.
_Size._--Capitulum four tenths of an inch long.
The following parts of the animal are described from some small and not well preserved specimens from Madeira, which I owe to the kindness of Mr. Lowe.
_Mouth._--Labrum highly bullate in the upper part, with large, inwardly pointed, unequal teeth. Mandibles, with four large, pointed, equal-sized teeth, with the inferior angle very narrow, ac.u.minated like a single spine. Maxillae, with three (?) large upper spines, of which the middle one is extremely strong and long, beneath which, there is a deep notch with a single strong spine, and with the whole inferior part square and much upraised, so as to stand on a level almost with the tips of the great upper spines.
_Cirri_ in a miserable state of preservation; first cirrus short, second cirrus with rami unequal, and I suspect the anterior one the longest; some of the other cirri also have unequal rami. The segments of the posterior cirri are not protuberant, they have on their anterior faces a single transverse row of bristles: in the upper segments, some of the spines in each dorsal tuft (which is much spread out), are _much_ thicker, though rather shorter than those on the anterior face. This peculiar structure is common to all five posterior cirri.
_Caudal Appendages._--I can only say that they are spinose on their summits.
_Affinities._--This species is allied to _P. eburnea_ in the rudimentary condition of its terga; in the disc-shaped basal end of its carina; and in the presence in some specimens, of a fissure-like line on the scuta parallel to their occludent margins. Its affinity, however, is closer to _P. fissa_, as is more especially shown by the remarkable arrangement of the spines on the five posterior cirri.
4. PaeCILASMA FISSA. Pl. II, Fig. 4.
_P. valvis 7; scuto utroque e duobus juxtapositis segmentis formato; segmento altero intus dentato: tergis brevibus, ter aut quater carina latioribus: carinae termino basali in disc.u.m parvum angustum infossum producto._
Valves 7; each scutum being formed of two closely approximate segments; of which one is internally toothed: terga short, three or four times as wide as the carina: carina with the basal end produced into a small, narrow, imbedded disc.
Spines on the segments of the posterior cirri arranged in single transverse rows.
Philippine Archipelago; Island of Bohol; parasitic on a spinose crab, found under a stone at low water; single specimen, in Mus., c.u.ming.
_General Appearance._--Capitulum gibbous, broadly oval, nearly a quarter of an inch long. Valves white, smooth, moderately thick, marked by the lines of growth. The occludent segments of the scuta, and nearly the whole of the terga, and the whole of the carina, enveloped in lemon-yellow membrane, tinged with orange, but the specimen had long been kept dry.
_Scuta_ formed of two, apparently always separate, segments, closely united, so that externally their separation is hardly visible, and does not allow of movement; the fissure thus formed runs almost in the line connecting the umbo and apex, (where in most species a ridge extends,) but a little on the carinal side of it. The occludent segment is narrowly bow-shaped, pointed at both ends, with the upper end projecting slightly beyond the apex of the lateral segment, and with the occludent margin regularly curved from end to end. The lateral segment is large, of an oval shape, with a narrow strip cut off on one side. Primordial valves very plain at the umbones of the lateral segments, but none are visible on the occludent segments; and this makes me believe that these two pieces are normally parts of a single valve; having only one specimen of _P. fissa_, I was not able to make out quite certainly whether the two segments are continuously united at their umbones by a non-calcified portion of valve, as is certainly the case with Dichelaspis. The basal margin of the lateral segment is narrow, inflected, and blends with the carino-tergal margin; it has an internal, prominent, basal rim, and towards the occludent margin a large, prominent, internal tooth. This internal basal rim is not parallel to the outer basal margin, but rises to a point a little way up the occludent margin, in the same manner as in _P. eburnea_, but in a lesser degree; in this latter species the peduncle is internally almost cut off by the large disc of its carina; here, on the other hand, it is internally almost cut off by these rims and the two large teeth of the lateral segments of the scuta.
_Terga_ sub-triangular, short, nearly half as broad as long; three or four times as wide as the carina, and rather wider than the occludent segment of the scuta; occludent margin single, arched; carinal margin slightly arched; basal angle bluntly pointed.